Use color if stdout is a tty

CHANGELOG.md

@@ -1,5 +1,7 @@
 ## HEAD (unreleased)
 
+- Don't print terminal color codes when output is not tty (https://github.com/zombocom/dead_end/pull/91)
+
 ## 2.0.1
 
 - Reintroduce Ruby 2.5 support (https://github.com/zombocom/dead_end/pull/90)

exe/dead_end

@@ -5,7 +5,6 @@ require "optparse"
 require_relative "../lib/dead_end"
 
 options = {}
-options[:terminal] = true
 options[:record_dir] = ENV["DEAD_END_RECORD_DIR"]
 
 parser = OptionParser.new do |opts|
@@ -46,6 +45,10 @@ parser = OptionParser.new do |opts|
     options[:record_dir] = v
   end
 
+  opts.on("--terminal", "Enable terminal highlighting") do |v|
+    options[:terminal] = true
+  end
+
   opts.on("--no-terminal", "Disable terminal highlighting") do |v|
     options[:terminal] = false
   end

lib/dead_end/display_invalid_blocks.rb

@@ -9,8 +9,8 @@ module DeadEnd
   class DisplayInvalidBlocks
     attr_reader :filename
 
-    def initialize(code_lines:, blocks:, io: $stderr, filename: nil, terminal: false, invalid_obj: WhoDisSyntaxError::Null.new)
-      @terminal = terminal
+    def initialize(code_lines:, blocks:, io: $stderr, filename: nil, terminal: nil, invalid_obj: WhoDisSyntaxError::Null.new)
+      @terminal = terminal.nil? ? io.isatty : terminal
       @filename = filename
       @io = io
 

lib/dead_end/internals.rb

@@ -28,14 +28,13 @@ def self.handle_error(e, search_source_on_error: SEARCH_SOURCE_ON_ERROR_DEFAULT)
       call(
         source: Pathname(filename).read,
         filename: filename,
-        terminal: true
       )
     end
 
     raise e
   end
 
-  def self.call(source:, filename:, terminal: false, record_dir: nil, timeout: TIMEOUT_DEFAULT, io: $stderr)
+  def self.call(source:, filename:, terminal: nil, record_dir: nil, timeout: TIMEOUT_DEFAULT, io: $stderr)
     search = nil
     Timeout.timeout(timeout) do
       record_dir ||= ENV["DEBUG"] ? "tmp" : nil

spec/integration/exe_cli_spec.rb

@@ -23,7 +23,7 @@ def exe(cmd)
 
     it "parses invalid code" do
       ruby_file = fixtures_dir.join("this_project_extra_def.rb.txt")
-      out = exe("#{ruby_file} --no-terminal")
+      out = exe(ruby_file)
 
       expect(out.strip).to include("Missing `end` detected")
       expect(out.strip).to include("❯ 36      def filename")
@@ -32,13 +32,13 @@ def exe(cmd)
     end
 
     it "handles heredocs" do
+      lines = fixtures_dir.join("rexe.rb.txt").read.lines
       Tempfile.create do |file|
-        lines = fixtures_dir.join("rexe.rb.txt").read.lines
         lines.delete_at(85 - 1)
 
         Pathname(file.path).write(lines.join)
 
-        out = exe("#{file.path} --no-terminal")
+        out = exe(file.path)
 
         expect(out).to include(<<~EOM.indent(4))
              16  class Rexe
@@ -50,6 +50,19 @@ def exe(cmd)
       end
     end
 
+    describe "terminal coloring" do
+      # When ruby sub shells it is not a interactive shell and dead_end will
+      # default to no coloring.
+
+      it "passing --terminal will force color codes" do
+        ruby_file = fixtures_dir.join("this_project_extra_def.rb.txt")
+        out = exe("#{ruby_file} --terminal")
+
+        expect(out.strip).to include("Missing `end` detected")
+        expect(out.strip).to include("\e[0m❯ 36  \e[1;3m    def filename")
+      end
+    end
+
     it "records search" do
       Dir.mktmpdir do |dir|
         dir = Pathname(dir)